Added a simple benchmarking suite. Run with 'make benchmark'

Makefile

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+# Make sure $JSSHELL points to your js shell binary in .profile or .bashrc
+# Most targets use commands that need a js shell path specified
+JSSHELL ?= $(error Specify a valid path to a js shell binary in ~/.profile: export JSSHELL=C:\path\js.exe or /path/js)
+
+# Version number used in naming release files.
+VERSION ?= $(error Specify a version for your release (e.g., VERSION=0.5))
+FREQUENCY ?= 440
+
+benchmark:
+	${JSSHELL} -j -e 'var FREQUENCY=${FREQUENCY};' -f dsp.js -f ./bench/bench.js -f ./bench/dft.js
+	${JSSHELL} -j -e 'var FREQUENCY=${FREQUENCY};' -f dsp.js -f ./bench/bench.js -f ./bench/fft.js
+	${JSSHELL} -j -e 'var FREQUENCY=${FREQUENCY};' -f dsp.js -f ./bench/bench.js -f ./bench/rfft.js
+
+clean:
+	rm -fr ./release

bench/bench.js

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+function benchmark(func, loopCount) {
+  loopCount = loopCount || 10000;
+
+  var start = Date.now();
+
+  for (var i = 0; i < loopCount; i++) { 
+    func();
+  }
+
+  var end = Date.now();
+  return end - start;
+}

bench/dft.js

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+var bufferSize = 2048;
+var sampleRate = 44100;
+var frequency = FREQUENCY || 440;
+
+var dft = new DFT(bufferSize, sampleRate);
+var osc = new Oscillator(DSP.SAW, frequency, 1.0, bufferSize, sampleRate);
+var signal = osc.generate();
+
+var duration = benchmark(function() { dft.forward(signal); }, 20);
+
+var peakBand = 0;
+
+for (var i = 0; i < dft.spectrum.length; i++) {
+  peakBand = (dft.spectrum[i] > dft.spectrum[peakBand]) ? i : peakBand;
+}
+
+var peakFreq = dft.getBandFrequency(dft.peakBand);
+
+print("Detected peak: " + peakFreq + " Hz (error " + Math.abs(peakFreq - frequency) + " Hz)");
+print("20 DFTs: " + (duration) + " ms (" + ((duration) / 20) + "ms per DFT)\n");

bench/fft.js

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+var bufferSize = 2048;
+var sampleRate = 44100;
+var frequency = FREQUENCY || 440;
+
+var fft = new FFT(bufferSize, sampleRate);
+var osc = new Oscillator(DSP.SAW, frequency, 1.0, bufferSize, sampleRate);
+var signal = osc.generate();
+
+var duration = benchmark(function() { fft.forward(signal); });
+
+var peakBand = 0;
+
+for (var i = 0; i < fft.spectrum.length; i++) {
+  peakBand = (fft.spectrum[i] > fft.spectrum[peakBand]) ? i : peakBand;
+}
+
+var peakFreq = fft.getBandFrequency(fft.peakBand);
+
+print("Detected peak: " + peakFreq + " Hz (error " + Math.abs(peakFreq - frequency) + " Hz)");
+print("10000 FFTs: " + (duration) + " ms (" + ((duration) / 10000) + "ms per FFT)\n");

bench/rfft.js

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+var bufferSize = 2048;
+var sampleRate = 44100;
+var frequency = FREQUENCY || 440;
+
+var fft = new RFFT(bufferSize, sampleRate);
+var osc = new Oscillator(DSP.SAW, frequency, 1.0, bufferSize, sampleRate);
+var signal = osc.generate();
+
+var duration = benchmark(function() { fft.forward(signal); });
+
+var peakBand = 0;
+
+for (var i = 0; i < fft.spectrum.length; i++) {
+  peakBand = (fft.spectrum[i] > fft.spectrum[peakBand]) ? i : peakBand;
+}
+
+var peakFreq = fft.getBandFrequency(fft.peakBand);
+
+print("Detected peak: " + peakFreq + " Hz (error " + Math.abs(peakFreq - frequency) + " Hz)");
+print("10000 FFTs: " + (duration) + " ms (" + ((duration) / 10000) + "ms per FFT)\n");